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Common star 17 EP

HD 22109

RA 53.4198° · Dec -0.3981° · star

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Score breakdown

· 4 badges
17 pts · Common
Common 22 pts → Uncommon
  • Deep red star +8
  • Star +3
  • On the zodiac +3
  • Orange K-type star +3
Total score 17

5 more points to reach Uncommon.

Badges

  • Star · +3
  • On the zodiac · +3
  • Orange K-type star · +3
  • Deep red star · +8

Trivia

Hard to believe

  • True brightness. It pours out about 2.9 million times as much light as the Sun. It only looks ordinary because it is so far away.

What it actually is

  • Spectral class. Its spectrum reads K0 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.

Find it in the sky

  • How to spot it. At magnitude 8.7 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Taurus.
  • Seen from everywhere. It sits almost on the celestial equator, so it can be seen from essentially anywhere on Earth.
  • Best time of year. It stands highest in the middle of the night around November — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out deep orange-red (B−V 1.5) — one of the coolest surfaces a star can have while still fusing.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 3800 K, against the Sun's 5778 K.

What's in a name

  • Its catalogue. The HD number is from the Henry Draper Catalogue, in which Annie Jump Cannon personally classified the spectra of nearly 400,000 stars — still the largest such feat by one person.

Properties

absmag
-11.32
bv
1.495
constellation
Tau
luminosity
2937649.652
mag
8.68
name
HD 22109
spect
K0

Nearby objects

About HD 22109

HD 22109 is a common star. It sits in the constellation Tau, shines at apparent magnitude 8.68 and has spectral type K0.

Its spectrum reads K0 — a K-type star. Orange K dwarfs are the marathon runners of the galaxy, burning steadily for tens of billions of years.

How to see it

Look for HD 22109 in the constellation Tau. At apparent magnitude 8.68, it is an easy target for binoculars.

Like any astronomical target, HD 22109 is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.

Why HD 22109 is a common star

HD 22109 scores 17 points on Spacedle's rarity scale, which places it in the common tier. Another 5 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, On the zodiac, Orange K-type star and Deep red star — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.